R. Leino, Hendrik Luttikhedde, P. Lehmus
May 29, 1998
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0
Influential Citations
12
Citations
Journal
Journal of Organometallic Chemistry
Abstract
Abstract The synthesis and molecular structure of rac -[ethylenebis(2-(thexyldimethylsiloxy)indenyl)]zirconium dichloride ( 4 ), is reported. In combination with methylaluminoxane (MAO), 4 forms an active catalyst system for homogeneous polymerization of ethylene and propylene. The high activity of 4 /MAO is retained at low [Al]:[Zr] ratios [(150–250):1]. Decreasing polymerization temperature or the [Al]:[Zr] ratio results in production of polyethylene having a high molecular weight shoulder in its molecular weight distribution (MWD). Deconvolution of the MWDs into a series of calculated Flory-distribution curves indicates that with this catalyst system ethylene is polymerized by three different types of active sites, whereas propylene is predominantly polymerized by two active sites. Complex 4 crystallizes in the indenyl-backward conformation. The ligand backbone adopts the expected C 2 symmetry.